Peak electrical demand is heavily dependent on air conditioning (A/C) loads. Summer 2000 in California demonstrated the seriousness of the peak electrical demand problem. Peak A/C loads played a key role in driving up electrical demand, which caused power outages and raised electricity rates.
Previous research has been conducted on the use of PCM slurries for electronics cooling and for district beating and cooling. However, the research has found that these PCM slurries are not suitable and too expensive to be used for shifting peak electrical load. PCM slurry flows have been researched by a number of individuals.
For example, D. P. Colvin, et al., S. K. Roy, et al., and researchers in Japan have studied the use of micro-encapsulated slurries for cooling electronic components in defense applications. A micro-encapsulated particle is where a paraffin material is encapsulated by an outer coating. The outer coating is durable enough to insure that the particles do not coalesce once placed in the water. The drawback of these materials is cost. The cost of the micro-encapsulated particles is on the order of tens of dollars per pound, while the cost of commercial grade paraffins is much less. It is too expansive to be used for shifting peak electrical load type applications. Therefore, paraffin slurries are considered as the first choice for a PCM slurry system.
Choi, Cho, and Lorsch at Drexel University studied the use of PCM slurries for district heating and cooling applications. Recently, Dr. K. Cho in Korea studied the use of PCM slurries for the cooling of multi-chip modules (MCM). These researchers have used slurries with PCM concentrations ranging from 5 to 30 percent. Higher PCM concentrations lead to smaller storage tank requirements.
Therefore, it is desirable to develop a PCM slurry mixture with a higher PCM concentration, for example 30–40 percent or more.